Specific impulse increases with the velocity of reaction mass “fuel” due to the conservation of momentum, while the acceleration rate is limited by available energy. Because kinetic energy is ½*mass*velocity2, the available acceleration is inversely proportional to the velocity of the reaction mass. So traditionally, spacecraft propulsion can be optimized for acceleration (e.g. rocket fuel using lower velocity exhaust but providing higher acceleration) or specific impulse (e.g. ion propulsion using higher velocity exhaust but limited by available energy to lower acceleration). Thus, it is difficult to achieve good results for both acceleration and specific impulse. Furthermore, when using non-reusable reaction mass such as rocket fuel, much energy is wasted on accelerating the remaining reaction mass that will only be ejected later. Launching any object into low Earth orbit (LEO) has very large energy and dollar costs, thus it is optimal to reduce the weight need to be lifted or minimize the number of times fuel must be launched into space.
Therefore it is an object of the present invention to provide a method that allows for the high acceleration of a primary spacecraft through the low velocity ejecting of a plurality of subsidiary spacecraft. Each of the plurality of subsidiary spacecraft has a propulsion system, allowing the plurality of subsidiary spacecraft to be directed to a refueling point and reloaded onto the primary spacecraft to be reused. Because each of the plurality of subsidiary spacecraft is recycled, the average momentum transferred per kilogram of “fuel” lifted to LEO is actually higher than that of the best rocket fuel. Furthermore, eliminating the need to lift new, Earth sourced fuel into LEO provides enormous economic savings. The potential elimination of non-reusable reaction mass provides a large disruptive performance gain relative to current state of the art approaches, especially as the benefits of the present invention scale over time. Using the present invention, round trip shuttles between LEO and Martian low orbit could be achieved without any new fuel from Earth, allowing the economic case for Mars colonization to include the ability to export to Earth.